Change in idle noise?

My 2001 xj has a k&n air filter. Every 30 seconds or so the idle sounds much louder for about 10 seconds then it goes back to quite then repeats the cycle. I have cleaned the filter. Any thoughts on what it is?

Thank you,

Nate

My jeep has been making this noise since I bought it. My dad heard it and said some thing is going bad. I had cleaned the K&N per instructions and re-oiled about 3 months ago and I noticed the filter element looked rough. I was poking around under the hood yesterday trying to find where the sound was coming from and it sounded like the air intake. So i replaced yesterday and the change in idle stopped. Weird. I guess lack of air flow?

Is your ac or defroster on?

What air intake did you replace?

It was a k&n. And if i turn the ac on it does change the idle every 30 seconds but nothing like what it was doing before.

What kind of noise? The A/C compressor will bump up the idle occasionally like stated above. If you have a higher flow filter or intake it will make a different sound.